I have both the TT and OS, in fact I flew both today.
I actually had a bit of problem starting the OS as it was pretty cold out. The TT fired right up.
Power wise I really can't tell the difference between the two (of course they are on different airplanes. OS on a Hobbico Brighstar and TT on a Seagull Spacewalker II)
As far as I can tell the only real difference is the remote needle valve on the OS and the price.
PS: when I say OS I am reffering to the 46AX.